Field of the Invention
The present invention relates to a waterproof control apparatus, which is a vehicle electronic control apparatus to be provided, for example, in an engine room, and particularly to a waterproof control apparatus having a respiratory ventilation structure that protects a waterproof-seal structure by interposing a water-repellent filter between the outer air and a waterproof-watertight case including a heat-generating component.
Description of the Related Art
A waterproof control apparatus is known in which a circuit board is watertightly contained in a case configured with abase and a cover, in which circuit components including a heat-generating component and an external-wiring connector housing, part of which is exposed from the case, are mounted on the circuit board, and in which a waterproof sealing material is provided on the respective joint surfaces among the base, the cover, and the connector housing. In the waterproof control apparatus, in order to prevent an air-pressure difference between the respective air pressures in the inside and the outside of the case, which is caused by a temperature rise in the heat-generating component in the case, from deforming the structure of the case or damaging the watertight sealing structure thereof, a water-repellent filter is provided on the cover or the base so that air inside the case is exposed to the outer air. The water-repellent filter is formed of a flat porous material including a plurality of fine pores for preventing water drops from intruding into the case and for letting the air freely pass therethrough; a mounting structure has been contrived so that the porous material is not stained through direct water pouring.
A waterproof control apparatus including a water-repellent filter provided on the cover is one of the configurations that have been widely put into practice; however, because a cover is a part that is mostly liable to become subject to direct water pouring, there has been a problem that a ventilation structure that can withstand direct water pouring due to high-pressure washing or the like is required and the ventilation structure is complex and expensive. A waterproof control apparatus including a water-repellent filter provided on the back-side portion of a base is another configuration. In this case, the water-repellent filter is provided at a position that is not liable to become subject to direct water pouring due to high-pressure washing; however, there has been a problem that in the case where the base is formed of sheet metal or an aluminum die-cast, it is difficult to bond and fix the water-repellent filter itself to the back-side portion. In the case of a base formed of resin, the water-repellent filter can readily be fixed through thermal welding; however, there has been a problem that heat generated in the case cannot be radiated through heat transfer.
The periphery of the connector with which a wire harness is connected is the most favorable place where both the position that is not liable to become subject to direct water pouring and the peripheral structure are taken into consideration.
For example, in “Ventilation Structure of Waterproof Case” disclosed in Japanese Patent Application Laid-Open No. 2000-228243 (Patent Document 1), as is seen in FIG. 1 thereof, a plurality of ventilation holes 23 for communicating the inside of a connecter 20 for a wire harness 19 to the air is formed in the connecter 20, and a water-repellent filter 24 having both air permeability and a waterproof property is integrated with the ventilation hole 23 through welding or the like. One or more communication holes 25 for communicating the inside of the connector 20 for the wire harness 19 to the inside of a waterproof case 11 are formed in a connector 17 for a circuit board 16 contained in the waterproof case 11. The inside of the waterproof case 11 and the inside of the connector 20 are communicated to the air through the ventilation hole 23 and the communication hole 25, respectively, so that water absorption due to a negative pressure is prevented and hence both a short-circuit in the connector 20 and a short-circuit in the circuit board 16 are prevented.
In “Waterproof Case” disclosed in Japanese Patent Application Laid-Open No. 2011-165748 (Patent Document 2), as is seen in FIGS. 9 and 12 thereof, a ventilation hole 20 is provided in a cover 18 of a waterproof case 300 containing an electronic board 15, and a respiration filter 10 configured with a double-face adhesive member 11 and a filter main body 12 is disposed on the outer surface of the cover 18. A slanted ventilation groove 26 communicating with the respiration filter 10 is formed in the cover 18, and a shielding plate 24 seals the respiration filter 10 and the ventilation groove 26, excluding the front end opening portion of the ventilation groove 26.
As a result, the respiration filter is configured with a ventilation groove having a labyrinth structure and a sealing member; therefore, unlike a conventional technology, it is not required to provide a plurality of ventilation holes in the case or a respiration filter across any two sides of the case; thus, it is allegedly claimed that because the respiration filter can be downsized, the cost can be suppressed and that clogging in the respiration filter can be reduced. The reference numerals utilized in each of the foregoing explanations for Patent Documents 1 and 2 are the ones utilized in each of the Patent Documents 1 and 2.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-228243 (paragraphs 0013 through 0016, and FIG. 1)
[Patent Document 2] Japanese Patent Application Laid-Open No. 2011-165748 (Paragraphs 0058 through 0063, FIGS. 8 through 12)
In “Ventilation Structure of Waterproof Case” disclosed in Patent Document 1, the water-repellent filter 24 is mounted on the connector 20 for the wire harness 19 and the respective insides of both the waterproof case 11 and the connector 20 are communicated to the air, so that water absorption is prevented from causing a short-circuit in the connector 20 and a short-circuit in the circuit board 16 . Accordingly, although provided at a place that is not liable to become subject to direct water pouring, the water-repellent filter 24 is disposed in a narrow space inside the connector 20; thus, there has been a problem that because the ventilation area is small, a difference between the pressure in the waterproof case 11 and the air pressure may be caused.
Moreover, because the waterproof control apparatus itself does not include any water-repellent filter, there has been a problem that the functional test of the apparatus alone cannot be performed.
In the case of “Waterproof Case” disclosed in Patent Document 2, the respiration filter (water-repellent filter) 10 having a labyrinth-structure ventilation hole is provided on the cover 18 at a position that is an immediate back side of the middle portion between the connector housings 17a and 17b; the to-the-air opening thereof is situated at the intermediate portion between the connector housings 17a and 17b. As a result, although the to-the-air opening is situated at a place that is not liable to become subject to direct water pouring, the cover 18 needs to have an opening wall face that abuts on the housings 17a and 17b and an inner wall face to which the respiration filter 10 is bonded and fixed and that has the ventilation hole 20; thus, there has been a problem that because the cover contour becomes complex, it is difficult to utilize the cover 18, as a sheet-metal cover, to say the least.
Moreover, depending on the direction in which the waterproof case is mounted, the to-the-air opening may become subject to direct water pouring, thus, there has been a problem that the waterproof case cannot be applied to that mounting angle.